Anything combustible needs to be kept how many feet away from a portable heater

What is the best way to improve the conclusion? add a sentence to the ending that summarizes the writer’s topic. add a sentence to the middle that reflects on the writer’s experiences. revise the final sentence to have a different tone. revise the first sentence to state a future goal.

How do i correct this sentence correctly?

Which sentence is punctuated correctly?  a.under a microscope; the organisms look a bit like ruffled tennis balls they have armored plates that fit together to make a round shape. b.when the water is disturbed; the organisms respond by glowing this makes swimmers look like floating beams of blue light. c.there is a bay in puerto rico that seems to light up at night; the light comes from tiny organisms in the water. d.the luminescence attracts visitors from around the world people are curious to see; this beautiful otherworldly sight.